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KMID : 0368419900330020119
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Journal of Plant Biology
1990 Volume.33 No. 2 p.119 ~ p.126
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The Analysis of Canavanine Centent in Leaves, Roots, and Xylem Exudate of Canavalia lineate
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Abstract
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The content of canavanine was measured and analyzed in leaves, roots and xylem exudate of Canavalia lineata. In non-nodulated plants, the cotyledons were removed after a week of sowing and the plants were grown for 3 weeks. The quantity of canavanine measured by canavanine specific-PCAF colorimetric assay was 9-10 μmol/g fresh wt. in leaves, 5-6 μmol/g fresh wt. in roots, and 0.3-0.5 μmol/㎖ in xylem exudate. When free amino acids of leaves, roots, and xylem exudate were analysed by HPLC, the relative proportion of asparagine plus glycine was the highest and canavanine was high secondarily. And the relative proportion of canavanine among total free amino acids was 30-35% in leaves and roots, and 12-13% in xylem exudate. In non-nodulated plants grown for 8 weeks, the canavanine content of each part was similar to that of 3-week-old plants. By the formation of nodules, the canavanine content of leaves, roots, xylem exudate, and nodules decreased apparently. In xylem exudate, the nitrogenous compounds were also analyzed. The relative contents of NO_3^-, free amino acids, and ureides (allantoin and allantoic acid) were 60-80%, 20-30%, and 5%, respectively. From these results, it can be assumed that canavanine is synthesized in the root of plant and nodulation affects the canavanine content. It is obvious that canavanine is considered one of the reduced-N forms transported via xylem.
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